1. Field of the Invention
This invention relates to capacitors. In particular, the invention relates to aluminum electrolytic capacitors.
2. Description of Related Art
Aluminum capacitors are popular in many applications due to low cost, versatility, high working voltages. They are useful in applications such as power supply filtering, low noise audio applications, and memory back-up. A capacitor typically consists of anode and cathode plates and a dielectric. The capacitance of a capacitor is directly related to the surface area of the anode and cathode plates. It is desirable to have a large surface area without increasing physical space for a given forming voltage and dielectric thickness.
Existing techniques to increase the surface area of an anode plate or foil include electrochemical etching. The etching roughens the surface of the foil and can increase the surface area hundred-fold. However, etching requires careful consideration. In addition, although the increase in surface area is large, it is still desirable to have even higher gain in surface area.
Therefore, there is a need to have a large surface area for the electrodes in capacitors.